60 BIOLOGY OF PNEUMOCOCCUS 



Yang's observation on saponin does not agree with that of Downie, 

 Stent, and White. 



Klein and Stone 721 made the interesting observation that while 

 pneumococci were not dissolved by saponin when tested in plain 

 broth culture, preliminary treatment of the cocci with cholesterol 

 rendered them susceptible to complete and rapid lysis by this sub- 

 stance. An excess of saponin inhibited the sensitization by choles- 

 terol and, conversely, an excess of cholesterol inhibited lysis by 

 saponin. The authors thought, on apparently good evidence, that 

 the action of such body fluids as blood and ascitic and pleural 

 fluids in sensitizing pneumococci to saponin lysis was attributable 

 to the cholesterol content. Klein 720 later reported that ergosterol 

 effected a similar sensitization. 



In 1930, Neufeld and Etinger-Tulczynska 983 explained more de- 

 tails of the process of bile-lysis. Using bile, sodium taurocholate, 

 and sodium linolenate, it was found that bile and bile-acid salts 

 possessed the greatest solvent action for pneumococci, although 

 soap and bile action were not always parallel. It was further ob- 

 served that the same antiseptics (one per cent phenol, one per cent 

 formalin, weak ammonium sulfide, acetone, and 0.05 per cent mer- 

 curic chloride), which interfere with bile-solubility, in general also 

 inhibited spontaneous autolysis as well as the solution of heat- 

 killed pneumococci by the bacteriolytic enzyme shown by Avery 

 and Cullen 41 to exist in Pneumococcus. Neufeld and Etinger- 

 Tulczynska stated that "the effect of antiseptics would indicate 

 that bile-solubility and action of autolytic ferments are related," 

 but opposed to the concept of parallel bile-solubility and autoly- 

 sis there is still evidence that the bile-salts have a lytic action of 

 their own, independent of autolytic ferments. The evidence is fur- 

 nished by the study of Goebel and Avery 520 on autolysis of Pneu- 

 mococcus. In addition to finding that autolysis was accompanied 

 by definite proteolysis and lipolysis, they observed that while so- 

 dium desoxycholate in excess inhibited the action of pneumococcal 

 protease, it did not inhibit the action of the lipase. Goebel and 



